Hello!
I'm meaning to make a pulsing LED circuit with a NE555 timer as I've seen some people do on youtube, but they only use 1 blue led, and I want to make one with 3 green leds.
My specs:
LEDS: 3 green leds, 2.9-3,6V 20mA 18000mcd
Batteries: 2 combined 9v pp3 batteries
Is there a hero out there that could explain to me how I need to change the resistors and such in order for my circuit to work?
The video im referring to:
Very thankful for any and all help!
Three LEDs take too much current for the chip, you would need to add a transistor to drive the three LEDs. Each LED would need its own current limiting resistor and you need a resistor on the base of the transistor.
Grumpy_Mike:
Three LEDs take too much current for the chip, you would need to add a transistor to drive the three LEDs. Each LED would need its own current limiting resistor and you need a resistor on the base of the transistor.
Hm, I see. Could I use 3 NE555's with 1 individual LED that are all powered on by a single on/off button?
You could, but they work work independent of each other (aka, will get out of phase). What is the trouble with a simple transistor?
septillion:
You could, but they work work independent of each other (aka, will get out of phase). What is the trouble with a simple transistor?
Oh, sure I could to that. I misread what Grumpy Mike said, A transistor would be fine. What kind would I need?
And could anyone make me a super simple drawing of what goes where in the circuit? I'm a electronic dummy 
That, only forget the "Arduino" part and connect out to the 555. And for 5V you can use whatever you like as long as you use the right resistor for the leds.
2N2222 is common in the US, the BC547 is common in Europe.
septillion:
That, only forget the "Arduino" part and connect out to the 555. And for 5V you can use whatever you like as long as you use the right resistor for the leds.2N2222 is common in the US, the BC547 is common in Europe.
Wow, thank you! I've decided to skip the arduino card tho, as the NE555 seems to do all the work that I wanted the card to do. Could you help me make one without it? You're super kind
So you have a 555 working?
Then just do as I said 
septillion:
only forget the "Arduino" part
Thank you for being patient, I'm very new to this, therefor I don't know all the terms, as an example I'm afraid I don't know what collector / emitter means.
Could I bother you with making it even simpler for me? I've attatched a image with what I thiiink the circuit might look like without the capacitators and transistor. Could you help me figure out what I'm missing?
No, connecting the leds to output and discharge is weird. Just connect a single led to output and GND.
For term about transistors, a little it of Google from your side would be appreciated
